1. Technical Field of the Invention
The present invention relates to an overhead conveyor system, and more particularly to a system of at least two overhead conveyors wherein a first conveyor having a plurality of workpiece carriers disposed thereon and operating at a first speed transfers workpiece carriers to a second conveyor operating at a second speed and into a closepack configuration.
2. Description of the Related Art
Conveying systems are typically used in manufacturing facilities to move work pieces from station to station along a predetermined path. Current conveyors may be used to transport elongated pieces such as furniture, doors, and the like through paint booths, curing ovens, and other workstations. These conveyors may be chain driven and have rotatable workpiece carriers.
Rotatable workpiece carriers are preferable for use with elongated workpieces because the workpieces can be rotated through a plurality of positions along a conveyor path, as desired. For instance, a rotating carrier may carry a relatively long piece of wood or fiberglass, having a length of five feet (5xe2x80x2). If the axis of the elongated piece travels parallel to the axis of the conveyor, the carriers would preferably be traveling on center distances of at least five feet (5xe2x80x2). This is called an openpack configuration. However, the elongated workpiece may be rotated ninety degrees so that its axis is transverse to the conveyor path. This is known as a closepack configuration. To conserve space and conveyor materials, it is desirable to shorten the distance between carriers, i.e. the center distance, in the closepack configuration, especially through inclines, declines, and selected workstations. A closepack configuration with shortened center distance is desirable because shorter lengths of conveyor track can be used and less overall manufacturing area is required for the manufacturing process. Therefore, a means for adjusting the center distance between workpiece carriers is needed to fully take advantage of the closepack configuration.
Typically on a single chain conveyor system including a plurality of workpiece carriers, the distances between carriers can be changed if the carriers are on a level portion of conveyor. In one type of conveying system a workpiece carrier having chain engaging pin is disengaged from a conveyor chain by bumping an engaged carrier into a previously stopped or disengaged carrier. An uncoupling bar or disengaging mechanism located on a front portion of the carrier contacts the rear of the disengaged cart and the mechanical linkage causes the carrier pin to raise or release from the conveyor chain. However, the distance between carriers cannot be changed while the carriers are moving along an inclined portion because disengaging the carrier pins on an incline will result in the carrier rolling backward along the conveyor path. In addition, changing the distance between workpiece carriers may require stopping an entire conveyor line if the carriers are all operating on a single chain. Thus, the result is that longer lengths of conveyor track are required to move through inclines and declines.
It is preferable to move the carriers into a closepack configuration with shorter distances between the centers of carriers when moving the carriers for instance through a paint booth, curing oven, drier, or the like without decreasing the throughput of workpieces. In a closepack configuration, carriers travel at relatively slower speeds than when in an openpack configuration. In addition smaller booths, ovens, or workstations are necessary thereby reducing manufacturing costs by, for instance, reducing building costs of the booths or ovens, heat loss, and ventilation equipment costs. Many overhead carriers move through an inclined or declined portion immediately prior to entering a paint booth, curing oven, or drier. Therefore a current problem exists as to positioning the carriers in a closepack configuration with shortened distances between the centers of the carriers when the carriers are moving through an inclined or declined position near a paint booth, curing oven, drier, or other type of workstation. In view of the deficiencies of known conveyor systems it is apparent that a system is needed for closepacking workpiece carriers in a manner wherein the center distance between the workpiece carriers is decreased therefore requiring less horizontal distance and conveyor length for conveyor inclines, declines, paint booths, baking ovens, dryers, or other workstations.
It is an objective of this invention to provide an overhead conveyor which allows closepacking of carriers along a flat, inclined, or declined portion of a conveyor system;
It is an even further objective of the present invention to provide a first conveyor moving at a first speed and a second conveyor moving at a second speed through an incline, a decline, and/or a work station;
It is yet an even further objective of the present invention to provide a conveyor system having a plurality of workpiece carriers in a first spaced configuration and a second, more closely spaced configuration.
It is still an even further objective of the present invention to provide a transfer unit for moving a plurality of workpiece carriers from a first conveyor to a second conveyor operating at a second speed.
Specifically, a multi-speed variable spacing conveyor system is provided which includes:
a first chain driven conveyor track for conveying a plurality of workpiece carriers therealong;
a second chain driven conveyor track wherein the track is for conveying a plurality of workpiece carriers therealong; and,
a transfer mechanism disposed between the first conveyor track and the second conveyor track for moving a plurality of carriers from the first conveyor track to the second conveyor track.
More specifically a method of transporting a workpiece carrier from a first conveyor to a second conveyor including the steps of:
operating a first conveyor at a first speed;
operating a second conveyor at a second speed;
operating a transfer mechanism at a speed equal to at least the first conveyor;
engaging a workpiece carrier along the first conveyor;
disengaging the workpiece carrier from the first conveyor;
forcing the workpiece carrier across the transfer mechanism to the second conveyor; and,
engaging the workpiece carrier with the second conveyor.
All of the above outlined objectives are to be understood as exemplary only and many more objectives of the invention may be gleaned from the disclosure herein. Therefore, no limiting interpretation of the objectives noted are to be understood without further reading of the entire specification, claims, and drawings included herewith.